You aced Biology 101, but genetic genealogy still makes you dizzy. Stop the whirlwind of haplotypes and helixes with our plain-English guide to DNA tests and what they mean for your pedigree.

You probably first heard about it a few years ago, but now it’s everywhere. Your society is sponsoring a lecture, fellow researchers were chatting about it at the Family History Center, or maybe you got an e-mail asking you to participate in a surname study. But you’re unsure about jumping on the DNA bandwagon. How does genetic genealogy work? How much does it cost? What about privacy? And why bother, anyway—will it really tell you something that traditional genealogy can’t?

Genetic genealogy complements traditional research—it’s not a substitute for squinting at microfilmed records and scouring family histories. You can’t simply take a DNA test, plug the results into an online database and discover your whole family tree back to the Dark Ages. The odds of finding a meaningful match in a DNA database aren’t particularly strong, since not many people have participated yet. And of course, DNA testing won’t reveal your ancestors’ names and birth dates. But it can help by confirming (or disproving) family legends and research discoveries. You can use it to find out if you’re distant cousin to other Kowalskis, to determine if the Colonial-era Massachusetts and Virginia Austin clans are connected, or to learn the truth behind that yarn about Granddad being adopted. Ultimately, genetic genealogy can save you time and money in researching the old-fashioned way.

That might sound counterintuitive if the $100 to $300 DNA-test price tag gives you sticker shock. But I became a believer when I conducted my own surname study. All Smolenyaks trace their roots to one of four families from a town in present-day Slovakia. But the paper trail peters out in the 1700s, so we couldn’t find a relationship. Imagine my surprise when DNA testing revealed that none of the families shared a common ancestor. My disappointment wore off, though, once I realized I’d been spared years of frustration trying to prove a false belief. DNA testing can steer your research by telling you which paths to avoid and hinting at where you should be looking. Fortunately, you don’t have to be a scientist to tap into this new genealogical resource. We’ll explain how genealogy-DNA testing works, how safe it is, and what it can (and can’t) tell you about your family.